Governor for fluid driven motor having reciprocating elements in rotor

ABSTRACT

A plurality of passages are formed in the rotor of an air motor. A reciprocating element is located in each of the passages for varying the flow of air through the passages in response to pressure of the air on the reciprocating element and further in response to the centrifugal force acting on the reciprocating elements, thereby regulating the speed of the rotor.

United States Patent Cameron GOVERNOR FOR FLUID DRIVEN MOTOR HAVING RECIPROCATING ELEMENTS IN ROTOR Inventor: William M. Cameron, Tokyo, Japan Nitto Kohki Company Limited Oct. 15, 1970 Assignee:

Filed:

Appl. No.:

Foreign Application Priority Data April 11, 1970 Japan ..45/30586 US. Cl. ..418/15, 418/42, 137/56 Int. Cl ..F01c 21/12, F03c 3/00, G05d 13/10 Field of Search ..418/40-44; 73/521; 137/56 References Cited UNITED STATES PATENTS 2/1911 Watson ..418/42 [451 Aug. 15, 1972 3,054,389 9/1962 Roggenburk ..41 8/42 3,242,936 3/1966 Kalb ..137/56 824,647 6/ 1906 Hamann ..418/42 824,648 6/1906 Hamann ..418/42 1,440,224 12/ 1 922 Kasley ..137/56 3,266,506 8/1966 Takahashi et al ..137/56 3,460,437 8/1969 Roggenburk ..418/41 Primary Examiner--Carlton R. Croyle Assistant Examiner-John J. Vrablik Att0rneyFlynn & Frishauf ABSTRACT A plurality of passages are formed in the rotor of an air motor. A reciprocating element is located in each of the passages for varying the flow of air through the passages in response to pressure of the air on the reciprocating element and further in response to the centrifugal force acting on the reciprocating elements, thereby regulating the speed of the rotor.

16 Claim, 11 Drawing Figures PATENTED Aus 15 m2 SHEET 2 BF 4 GOVERNOR FOR FLUID DRIVEN MOTOR HAVING RECIPROCATING ELEMENTS IN ROTOR This invention relates to air motors, and more particularly to an improved governor for air motors.

Air motors have a wide range of applications for general motor use, motor driven tools and the like, because they are superior to electric motors in that they experience no troubles due to overloads, they can provide high rotational speeds and control of the rotational speed may be easily adjusted by adjusting the air pressure. Air motors are also easy to operate and to repair. Further, they are smaller in size and weight than electric motors with equivalent output.

In air motors, however, a disadvantage is that rotational speed varies according to the change of load. An air governor is generally provided to obviate this defect. In a grinding tool, for example, grind stones are liable to break off due to the centrifugal force when the rotational speed exceeds a predetermined upper limit during no load rotation. A governor, therefore, is indespensable for this kind of tool to maintain the rotational speed below the fixed upper limit, even under no load rotation. The governor simultaneously prevents rotational speeds from being lowered due to an increase in the load by controlling the supply air.

Conventional governors, one example of which is shown in U.S. Pat. No. 3,421,412, are characterized in that an automatic switch system employed for the adjustment valve of the supplied air which is operated by the action of the fly wheel arranged on the end of the rotor shaft. The prior art governor, however, has a complex, large and heavy construction, thereby impeding the viewing angle of an operator and making it more difficult to handle. Thus operating efficiency is lowered.

The main object of the present invention is to provide an air governor for an air motor which is of simple construction and which provides accurate operation, and which can be constructed in a large part within the rotor of the motor to miniaturize the resulting motor assembly, thus obviating the defects of the prior art.

SUMMARY OF THE INVENTION According to a first aspect of the present invention, a fluid driven motor and governor arrangement includes a number of passages formed in the rotor and communicating with the air chamber of the motor. A reciprocating element is located in each of the passages for varying the flow of supply fluid through the passages in response to pressure of the fluid on the reciprocating element and further responsive to the centrifugal force acting on the reciprocating elements. Exhaust holes are formed in the housing to exhaust fluid from the rotor passages and out from the motor during operation. The location of the reciprocating element in the passages determines the exhaust of fluid.

According to a second aspect of the present invention, a fluid driven motor and governor arrangement includes a number of passages formed in the rotor and communicating with the air chamber of the motor. A source of supply fluid, such as compressed air, is coupled to the rotor passages and a reciprocating element is located in each of the passages for varying the flow of the supply fluid through the passages to the air chamber responsive to the pressure of the supply fluid on the reciprocating elements and further responsive to the centrifugal force acting on the reciprocating elements. At least one exhaust hole is formed in the housing of the motor to exhaust fluid from the chamber and out from the motor. The position of the reciprocating element in the passages varies the flow of supply fluid to the air chamber of the motor, thereby controlling the speed of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show the preferred embodiments of the governor of the air motor according to the present invention in which:

FIG. I is a cross sectional view of a first embodiment of an air motor assembly member in accordance with the present invention;

FIG. 2 is a plane view of the air motor assembly member shown in FIG. 1;

FIGS. 3 and 4 are cross sectional side views with the motor covers removed, illustrating the operation of the air motor of FIGS. 1 and 2;

FIG. 5 is a cross sectional view of a second embodiment of an air motor in accordance with the present invention;

FIG. 6 is a cross sectional view of a third embodiment of an air motor assembly member according to the present invention;

FIG. 7 is a plane view of the air motor assembly member shown in FIG. 6;

FIGS. 8 and 9 are cross sectional side views illustrating the operation of the air motor of FIGS. 6 and 7;

FIG. 10 is a cross sectional view of a fourth embodiment of an air motor according to the present invention; and

FIG. 11 is a graph showing the efficiency of a general air motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 4 illustrate an air motor utilized in a grinder tool. There are many other uses, however, for such an air motor. The air motor is comprised of the air chamber 1 enclosed with the side plates 2a and 2b and the cylinder 3, rotor 4, vanes 5, rotor shaft 6 and the body 7 covering the same. In FIGS. 1 to 4, 8a, 8b, 9 and 10 denote the upper cover, the grip of the tool and the grinder, respectively. The grinder 10 is operatively coupled to the shaft 6 of the air motor.

The cylinder 3 is provided with a notch portion 11, shown in FIG. 2, which is in communication with air supply holes (i.e., passages) 12 and 13 bored in the grip 9 and the body of the tool. A plurality of exhaust holes 14 (four holes are bored according to the present embodiment) are bored between the vanes 5 in the radial direction of the rotor 4 and in the .perpendicular direction relative to the axial direction of the rotor shaft 6. The exhaust holes 14 are connected to one another and communicate with the air chamber 1. Exhaust holes and 15b are bored in the rotor in a direction in parallel with the axial direction of the rotor shaft 6. Exhaust holes 15a and 15b are coupled to exhaust holes 14 to respectively lead the exhaust air off in both upper and the lower directions relative to the axial direction of the rotor. Portions of the upper and lower side plates 2a and 2b which are in registration with the rotor exhaust holes a and 15b are provided with the are shaped grooves 16a and 16b and are bored with exhaust holes 17a and 17b, as clearly shown in FIG. 1. Ex-

haust holes 200 and b are bored in the upper and lower covers 811 and 8b, respectively. The are shaped portions on the grooves 16a and 16b of the side plates are large enough to accommodate a number of exhaust holes 17a or 17b arranged as shown in FIG. 2. The size of the grooves 16a and 16b and the size of the exhaust holes 17a and 17b depend upon the amount of the air to be exhausted and the size and capacity of the motor.

A ball 18 is enclosed inside each exhaust hole 14. The ball 18 moves outwardly due to the centrifugal force caused by rotation of the rotor 4 until its outward movement is stopped by a pin 19 mounted in the exhaust hole 14.

The automatic adjustment means for adjusting the amount exhaust of exhaust air is described below:

1. The air is supplied to the cylinder 3 through the supply passage 12 of the grip 9, the supply passage 13 of the body 7 and the notch portion 11 of the cylinder 3 (position A in FIG. 2).

2. The air is compressed in the air chamber 1 surrounded by the cylinder 3, the rotor 4, the upper and the lower side plates 2a and 2b and the vane 5. The rotor 4 rotates (see position B in FIG. 2).

3. As a result, the are shaped grooves 16a and 16b of the upper and the lower side plates 20 and 2b become in registration with the exhaust holes 15a and 15b of the rotor (see FIG. 1 and position C in FIG. 2).

4. The ball 18 moves in hole 14 in the direction towards the rotor shaft 6 due to the compressed air in spite of the centrifugal force, as shown in FIG. 3, if the rotational speed of the rotor 4 is low (for example, 3,000 r.p.m. in FIG. 11). Accordingly, the air from chamber 1 is exhausted out in the direction of the arrow and the rotational speed of the motor increases. 7

5. If the rotational speed of the rotor is high (for example 12,000 r.p.m. in FIG. 11) the ball l8 moves outwardly due to centrifugal force until it is stopped by the pin 19, the centrifugal force, in this case, overcoming the pressure of the compressed air from chamber 1. Accordingly, since the ball 18 at least partially blocks holes 15a and 15b, the amount of exhaust air is thereby automatically adjusted to be smaller and the rotational speed of the motor is caused to decrease. An equilibrium condition is eventually reached.

The air is exhausted out of the motor through the exhaust holes 170 and 17b in the side plates 20 and 2b, respectively, and the holes 20a and 20b of the upper and the lower covers 8a and 8b, respectively.

FIG. 5 shows another embodiment of the present in-' vention based on the governor of FIGS. 1 to 4, but which is provided with an additional exhaust air passage. The same reference numerals are used to designate corresponding elements throughout the drawings. The side plate 2b has a groove 50 formed therein. An exhaust hole 51 is bored in side plate 2b which connects to the air chamber 1 via groove 50. The cover 8b (partially shown in FIG. 5) is provided with a valve 52 which cooperates with the opening 510 of the exhaust hole 51. Opening 51a is shaped to properly seat with the valve 52. The valve 52 moves vertically in the directions of the arrow 52a by automatic or mechanical means (not shown). When the exhaust hole 51 is closed by valve 52, the same exhaust operation as that of the embodiment of FIGS. 1 to 4 is provided. when the exhaust hole 51 is opened, larger amounts of air is exhausted through hole 20b than in the embodiment of FIGS. 1-4. Thus, the rotational speed of the rotor is more easily and quickly increased with the embodiment shown in FIG. 5. This arrangement provides a more responsive governor operation. In FIG. 5, the exhaust hole 51 is positioned on the lower side plate 212,

but it can be alternatively positioned on the upper side plate 2a, or a hole 51, or the like, can be located on both side plates 2a and 2b.

Another embodiment of the present invention will be described with reference to FIGS. 6 to 9. This embodiment attains the same effects at the previous embodiments, but by adjustment of the amount of supply air, whereas in the previously described embodiments the rotational speed of the rotor was controlled by adjustment of the exhaust air.

The construction of the air governor of FIGS. 6 to 9 is similar to that of FIG. 1, but the different parts are explained below. Corresponding elements in FIGS. 1 and 6 are designated by the same reference numerals. The cylinder 3 is connected to a supply groove 61 as shown in FIG. 6. Cylinder 3 has holes 62a and 62b formed therein which couple the supply groove 61 with the upper and the lower side plates 20 and 2b, respectively. The upper and the lower side plates 2a and 2b have grooves 63a and 63b, respectively, bored therein which couple to the holes 62a and 62b, respectively. The upper and lower side plates 2a and 2b further have grooves a and 65b, respectively, formed therein, holes 64 and 641) being formed in the upper and lower side plates, respectively. Hole 64a couples groove 63a to groove 65a, and hole 64b couples groove 63b to groove 65b. The various grooves and holes are also indicated in FIG. 7.

A plurality of supply holes 66 corresponding to the exhaust holes 14 in FIG. 1 are radially bored in the rotor 4 in the perpendicular direction relative to the rotor shaft 6. The supply holes 66, however, are closed by means of the stopper member 67 enclosing the ball 18 therein. Further, the rotor 4 is bored with holes 68a and 68b which are parallel with the axis of shaft 6, for connecting the supply hole 66 with the grooves 65a and 65b of the upper and the lower side plates respectively. A slanting hole 69 is formed in rotor 4 for connecting the supply hole 66 with the air chamber 1. The cylinder 3 and the body 7 are provided with the exhaust holes 70 and 71, respectively.

The embodiment of FIGS. 6-9 operates as follows:

I. The rotor 4 rotates and the holes 680 and 68b become engaged with the grooves 65a and 65b of the upper and the lower side plates 2a and 212, respectively, thus permitting air to be supplied to holes 680 and 68b.

. If the rotor speed is low, the ball 18 moves toward the axis of the shaft 6 against the centrifugal force of the rotor as shown in FIG. 8. Accordingly, the input air is supplied to the air chamber 1 through the groove 61 of the cylinder 3, the holes 62a and 62b of the upper and the lower side plates, grooves 63a and 63b, the holes 64a and 64b, the grooves 65a and 65b, the supply holes 68a and 68b and the slanting hole 69. When the speed is low and the ball moves towards the axis of the rotor shaft 6, the ball does not influence the supply air and thus, the rotational speed of the rotor is increased.

3. When the rotor speed is high, the ball 18 moves outwardly as shown in FIG. 9 due to the centrifugal force. Thus, the air supply to the slanting hole 69 is at least partially obstructed by the ball 18, 10

, control by adjusting the input air flow, whereas the embodiments of FIGS. 1-5 provide speed control by adjusting the exhaust air flow.

Another embodiment of the present invention will be explained with reference to FIG. 10. This embodiment is similar to that of FIGS. 69, and only a partial view thereof, showing the additional features, is given in the drawings. The governor of FIG. 10 is provided with an additional air supply passage. The embodiment of FIG. 10, in addition to the elements of the governor shown in FIGS. 6-9, has an extra air supply passage 80 formed in cylinder 3 which connect the groove 61 of the cylinder 3 directly with the air chamber 1 in the cylinder. As a result, the amount of the supplied air is high and the rotational speed of the rotor tends to increase. A valve may be provided in passage 80 to vary the air flow therethrough.

Various shapes of balls 18 are applicable for use in the present invention if they are movable by means of the centrifugal force of the rotor, and if they are able to obstruct (and/or block) the perpendicular hole and the slanting hole.

The air motor governor of the present invention provides many advantageous effects. The main advantageous effects are as follows:

1. The governor is installed inside the air motor and integral therewith by making efficient use of the rotor, so that the construction of the whole body is simple, and the air supply and the air exhaust operations are accurately carried out.

2. The resulting air motor is therefore compact and light in weight, thus providing a wide range of applications as a power source for various portable tools such as grinders, sanders, drills, and the like.

3. The air motor of the present invention additionally provides all of the advantages of the prior art motors.

The air motor provided with the governor of this invention can be designed to accurately operate at the optimum power conditions as shown by the curves of FIG. 11. The present governor enables more accurately controlled operation and thus, the operating effeciency ofthe air motor is very high.

What is claimed is:

I. In a fluid driven motor having a housing means forming a chamber therein, a source of supply fluid coupled to said chamber, and a rotor shaft having a rotor thereon, said rotor shaftand rotor being rotatably mounted in said chamber;

a governor arrangement comprising:

a plurality of passages formed in said rotor and communicating with said chamber, said passages receiving said supply fluid after said supply fluid has imparted rotary forces to said rotor;

a free moving reciprocating element in each of said passages for varying the flow of said fluid through said passages responsive to the pressure of said fluid on said reciprocating elements and responsive to the centrifugal force acting on said reciprocating elements, said centrifugal force acting on said reciprocating elements in a direction opposite to said pressure of said fluid; and

means to exhaust fluid from said rotor passages and out from the motor.

2. A motor according to claim 1 wherein said rotor passages each include:

a first passage formed in said rotor in the radial direction of said rotor, said reciprocating element being enclosed in said first passage, said first passage being dimensioned such that a clearance always exists between said element and said first passage for flow of said fluid therebetween; and

a second passage formed in said rotor and communicating said first passage with said exhaust means which includes exhaust holes formed in said housing means.

3. A motor according to claim 1 wherein said reciprocating element is a ball and comprising a pin in each of said first rotor passages to retain said ball in said rotor passage.

4. A motor according to claim 1 wherein said source of supply fluid is a source of compressed air.

5. A motor according to claim 1 wherein said exhaust means includes exhaust holes formed in said housing means and engageable with said respective rotor passages during portions of the rotation of said rotor.

6. A motor according to claim 5 wherein said housing means includes upper and lower side plates, each side plate having exhaust holes formed therein.

7. A motor according to claim 1 wherein said housing means includes an additional exhaust hole coupled to said chamber; and including means for selectively opening and closing said additional'exhaust hole independent of the operation of said reciprocating element to selectively exhaust fluid from said motor chamber.

8. A motor according to claim 7 wherein said housing means includes upper and lower side plates, said additional exhaust hole being formed in at least one of said side plates.

9. In a fluid driven motor having a housing means forming a chamber therein, a source of supply fluid, and a rotor shaft having a rotor thereon, said rotor shaft and rotor being rotatably mounted in said chamber;

a governor arrangement comprising:

a plurality of passages formed in said rotor and communicating with said chamber;

means coupling said source of supply fluid to said rotor passages for feeding supply fluid thereto;

a free moving reciprocating element in each of said passages for varying the flow of said fluid through said passages and to said chamber responsive to the pressure of said fluid on said reciprocating elements and responsive to the centrifugal force acting on said reciprocating elements, said reciprocating elements being located in their respective passages such that said centrifugal force acting thereon is in a direction opposite to the pressure of said fluid thereon; and

at least one exhaust hole formed in said housing means to exhaust fluid from said chamber and out from the motor.

10. A motor according to claim 9 wherein said means coupling said source of supply fluid to said rotor passages includes at least one supply passage formed in said housing means which engages with said respective rotor passages during portions of the rotation of said rotor.

11. A motor according to claim 9 wherein said housing means includes upper and lower side plates, each side plate having at least one supply passage formed therein.

12. A motor according to claim 9 wherein said rotor passages each include:

a first passage formed in said rotor in the radial direction of said rotor, said reciprocating element being enclosed in said first passage;

a second passage formed in said rotor and coupling said source of supply fluid to said first passage; and

a third passage formed in said rotor coupling said supply supply fluid from said first passage to said chamber, said reciprocating element varying the flow of fluid to said third passage.

13. A motor according to claim 9 wherein said reciprocating element is a ball and wherein said second passage is a chamber formed .within said rotor and which does not directly communicate with said housing chamber said second chamber being dimensioned such that a clearance always exists between said ball and a wall portion of said second chamber.

14 A fluid driven motor governor according to claim 9, comprising means coupling said source of supply fluid directly to said chamber; and means for selectively opening and closing said direct supply means independent of the operation of said reciprocating element to selectively feed supply fluid to said chamber.

15. A motor according to claim 9 wherein said housing means includes upper and lower side plates, said direct supply means being formed in at least one of said side plates.

16. A motor according to claim 9 wherein said source of supply fluid is a source of compressed air. 

1. In a fluid driven motor having a housing means forming a chamber therein, a source of supply fluid coupled to said chamber, and a rotor shaft having a rotor thereon, said rotor shaft and rotor being rotatably mounted in said chamber; a governor arrangement comprising: a plurality of passages formed in said rotor and communicating with said chamber, said passages receiving said supply fluid after said supply fluid has imparted rotary forces to said rotor; a free moving reciprocating element in each of said passages for varying the flow of said fluid through said passages responsive to the pressure of said fluid on said reciprocating elements and responsive to the centrifugal force acting on said reciprocating elements, said centrifugal force acting on said reciprocating elements in a direction opposite to said pressure of said fluid; and means to exhaust fluid from said rotor passages and out from the motor.
 2. A motor according to claim 1 wherein said rotor passages each include: a first passage formed in said rotor in the radial direction of said rotor, said reciprocating element being enclosed in said first passage, said first passage being dimensioned such that a clearance always exists between said element and said first passage for flow of said fluid therebetween; and a second passage formed in said rotor and communicating said first passage with said exhaust means which includes exhaust holes formed in said housing means.
 3. A motor according to claim 1 wherein said reciprocating element is a ball and comprising a pin in each of said first rotor passages to retain said ball in said rotor passage.
 4. A motor according to claim 1 wherein said source of supply fluid is a source of compressed air.
 5. A motor according to claim 1 wherein said exhaust means includes exhaust holes formed in said housing means and engageable with said respective rotor passages during portions of the rotation of said rotor.
 6. A motor according to claim 5 wherein said housing means includes upper and lower side plates, each side plate having exhaust holes formed therein.
 7. A motor according to claim 1 wherein said housing means includes an additional exhaust hole coupled to saiD chamber; and including means for selectively opening and closing said additional exhaust hole independent of the operation of said reciprocating element to selectively exhaust fluid from said motor chamber.
 8. A motor according to claim 7 wherein said housing means includes upper and lower side plates, said additional exhaust hole being formed in at least one of said side plates.
 9. In a fluid driven motor having a housing means forming a chamber therein, a source of supply fluid, and a rotor shaft having a rotor thereon, said rotor shaft and rotor being rotatably mounted in said chamber; a governor arrangement comprising: a plurality of passages formed in said rotor and communicating with said chamber; means coupling said source of supply fluid to said rotor passages for feeding supply fluid thereto; a free moving reciprocating element in each of said passages for varying the flow of said fluid through said passages and to said chamber responsive to the pressure of said fluid on said reciprocating elements and responsive to the centrifugal force acting on said reciprocating elements, said reciprocating elements being located in their respective passages such that said centrifugal force acting thereon is in a direction opposite to the pressure of said fluid thereon; and at least one exhaust hole formed in said housing means to exhaust fluid from said chamber and out from the motor.
 10. A motor according to claim 9 wherein said means coupling said source of supply fluid to said rotor passages includes at least one supply passage formed in said housing means which engages with said respective rotor passages during portions of the rotation of said rotor.
 11. A motor according to claim 9 wherein said housing means includes upper and lower side plates, each side plate having at least one supply passage formed therein.
 12. A motor according to claim 9 wherein said rotor passages each include: a first passage formed in said rotor in the radial direction of said rotor, said reciprocating element being enclosed in said first passage; a second passage formed in said rotor and coupling said source of supply fluid to said first passage; and a third passage formed in said rotor coupling said supply supply fluid from said first passage to said chamber, said reciprocating element varying the flow of fluid to said third passage.
 13. A motor according to claim 9 wherein said reciprocating element is a ball and wherein said second passage is a chamber formed within said rotor and which does not directly communicate with said housing chamber said second chamber being dimensioned such that a clearance always exists between said ball and a wall portion of said second chamber.
 14. A fluid driven motor governor according to claim 9, comprising means coupling said source of supply fluid directly to said chamber; and means for selectively opening and closing said direct supply means independent of the operation of said reciprocating element to selectively feed supply fluid to said chamber.
 15. A motor according to claim 9 wherein said housing means includes upper and lower side plates, said direct supply means being formed in at least one of said side plates.
 16. A motor according to claim 9 wherein said source of supply fluid is a source of compressed air. 